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(No Model.)

J. D. DARLIN PROCESS OF UTILIZING NITBR CAKE OR B ACID SULFA'I'ES.

No. 541,598. Patented June 25, 1895.

INVENTOR UNITED STATES PATENT I OFFICE JAMES n-DARLI G, or PHILADELPHIA,P NNsrLvAN-I 'AssIcNoR To f HARRISON BROTHERS-8a or SAME PLACE.

PROCESSOF UTiL'l ZING YNIITER-CAKEOR OTHER ACIDSULFATES.

sPEcIFicA'rroN forming part r Letters Patent No. 541.598, dated J'une25, 1,895.

Application tiled January 8,1895. Serial 1%. 534,198. (N3 specimens.) I

To aZZ whom it may concern.-

Be-it know-n that 1, JAMES D. DAR1JING,. 0f the city of Philadelphia, inthe State of Penn sylvania, have invented acertain new and usefulProcess for'UtilizingNiter-Cake or. other Acid Sulfates and ObtainingValuable By-Products Therefrom, 0t which the following is aspecification. p r In the commercial manufacture of' nitric acid, andalsoof sulphuric acid, when nitrate of soda is employed to furnishthe'nitrogen compounds required, the resulting "by-product has approximatelythe composition of bisulphate of soda, although there is usually anexcess of sulphuric acid pres-- ent, even beyond the amount which wouldbe due tothe formula NaHSOp This byproduct, termed niter-cake, is oftrifling commercial value, and various methods have been attempted toutilize it, but so far as I- am aware, all of such methods arerelativelycostly and the commercial results therefrom have beenneithersati'sfactory nor profitable.

My process is principally addressed to the economical and efficienttreatment of nitercake for the derivation of two by-product's, viz:neutral sulphate of. soda (Na SO and chlorine gas. the utilization ofother acid sulphates, with corresponding results.

To this'end my process consists in electrically decomposing a solutionwhich contains a base similar to that of the acid sulphate, and causingsuch base to travel (by electrical action) toward, and combine with, theacid sulphate, juntil the desired neutralization thereof has beenefiected. The other deriva;

tive of the electrolyticdecomposition is con ducted awayunderp'ropercontrol, and'recovered as a distinct by-product. For convenience ofnomenclature,1 term the solution which is to be thus decomposed, (inorder to furnish an additional quantity of base to the acid sulphate,)the base-supplying electrolyte, and I term the transfer of the base fromthe region of its decomposition -to the region of rel-combination, theelectrolytic travel thereof.

In the accompanying drawing 1 have representedin vertical sectionatypical apparatus adapted to the conduct of my process, but I It may,however, be applied to do not limit myself to e em ioymentbrthisshown insaid-drawing.

'A, represents a tankof wood or slate, di-

vided into three compartments by means of the transverse partitions, B,B. These partitions should be in whole or in part porous, to an extentsufficient to allow of electrolytic travel, unaccompanied by anyexcessive increase in electrical resistance; In the central compartment(which is the decomposing cell)-isplaced a carbon electrode, D, whichconstitutes the positive pole, and in each of the {othercom-,- partmentsis placed an electrode, E, which may be of sheet lead,constituting-negative is provided .with a close fitting cover, F,havingan outlet, G, and a ,feed orifice, H. The,

"poles. The centralor positive compartment central compartment is filledwith the basesupplying electrolyte, whichis a saturated solutionoffsodium chloride,fland the two adjacent compartments are filled "tothe same level with aso'lution of miter-cake. The physi; calintermingling of the two solutions, as such, is practically prevented bythe partitions, B, but on passing a suitable current of electricity fromthe positive to the negative pole of the apparatus, the sodium chloridesolution in the central compartment is decomposed and the sodium, iscaused to travel;

through the porous partition to the region of the niter-cake solution,where it combines with the surplus sulphuric acid and forms eutralsulphate of soda; while the liberate chlo-,

.rine passes 0% through the outlet pipb,G, to

any convenient receptacle, where it .inay be absorbed by lime, orcondensed into liquid form directly, or utilized in any desired man--'ner. As the process proceeds, chloride of sodium may be suppliedthrough the feed orifice, H, in the cover, F, and the process may bethus continued until the entire charge ofacid sulphatecontained in thenegative compartment has been neutralized and the desired productobtained. The solution of neutral sulphate is .then drawn ofiand'afte'rfiltering to free it from precipitated iron and otherimpurit ieaisallowed to crystallize." The too mother liquor, with the addition of aproper to'a certain extent of the sulphuric acid takes place and oxygenis liberated at the positive pole, which action tends vto disintegratethe carbon electrode. There is also the further liability to a physicalintermingling of the two solutions, so that at the close of the processthe neutral sulphate would contain more or less of the sodium chloridediffused lhrough it. These objections are, however, not vital, and henceI do not limit my claim to the employment ofthe specified type ofapparatus.

I do not limit myself to the employment of this process in connectionwith niter-cake, as it may be applied to the treatment of other acidsulphates for the production of neutral salts. It isof course necessarythat the basesupplying electrolyte should insuch case be of a characterto correspond to the salt to be neutralized. 1 q I claim- 1. Thehereinbefore described process for the treatment of acid sulphates,which con-' sists in electrically decomposing an electrolyte containinga similar base to that of the sulphate, andtransferring said base to thesulphate by electrolytic travel, substantially as described. 7

2. The hereinbefore described process for the treatment of acidsulphates,which consists in electrically decomposing an electro-' lytecontaining a similar base to that of the sulphate, transferring saidbase-to the sulphate by electrolytic travel, and recovering the gaseousproduct of said decomposition of the basesupplying electrolyte,substantially as described.

9 a JAMES D. DARLING.

iVitnesses:

HERMAN G. SGHAUCHE,

SIDNEY S. EMERY.

